1. Field of the Invention
This invention is in the field of magnetic recording media such as magnetic tapes or disks and provides an improved binder composition.
2. Description of the Prior Art
In the field of modern magnetic recording, the tendency is towards increasing the recording density and using shorter wavelength recording signals. For use therewith, a coated type magnetic recording medium has been provided in which the magnetic layer is produced by applying a coating of a magnetic paint on a non-magnetic base with small sized magnetic particles dispersed in the magnetic layer. The small size is desired to achieve a higher packing density and a resulting improved smoothness or lubricity of the magnetic layer.
With improved smoothness or lubricity of the magnetic layer, the spacing loss is advantageously lowered. However, certain inconveniences arise in the tape running and durability characteristics. When the magnetic layer is too smooth, the recording medium tends to be affixed to, for example, the magnetic head, guide posts, or to the cylinder for a rotating head. In addition, the effective contact area is increased, thereby increasing the frictional coefficient so that tape running is affected adversely or inhibited. The increase in frictional coefficient results in increased tape tension causing powder to flake off, a deteriorated profile, or head clogging as well as an adverse effect on the tape durability.
With a magnetic recording medium used for high density recording, it is necessary to procure to some extent a proper volumetric density of the magnetic powders of the magnetic layer from the viewpoint of electromagnetic conversion characteristics. In this case, an increase in the specific surface area caused by comminution of the magnetic powders deteriorates the coating properties of the magnetic layer in an undesirable way. Thus, comminution of the magnetic powders deteriorates the running of the magnetic tape or the physical properties of the magnetic layer.